1. Field of the Invention
The invention is related to the field of broach assemblies and in particular to a pot type broach assembly having longitudinal sub-holders to which the broach members are attached.
2. Description of the Prior Art
Pot broaching is defined as a machining operation in which the part to be machined is passed through the hollow interior of an assembly of broaching tools. These assemblies as taught by Iversen in U.S. Pat. No. 2,516,518 consist of single or multi-tooth broach inserts which are mounted in a tool holder. A plurality of tool holders are connected to each other along a longitudinal axis. The broach inserts of each successive tool holder removes an additional quantity of material of the part being machined as it is passed through the pot type broach assembly.
Conventionally each broach insert is individually secured in a precision bore or slot provided in the tool holder and secured in place by a socket head bolt. This requires that the body section of each broach insert be sufficient to allow the tapping of threads in the base of the broach inserts for blots which are strong enough to secure the broach insert to the tool holder during machining of the part.
A problem that exists with the current pot type broaches is that this method does not permit the attachment of broach inserts to the tool holder when they are too thin to have tapped holes for receiving bolts having the required strength.
The invention is a pot type broach assembly which solves this problem by using a broach insert sub-holder which has sufficient width to be tapped with holes for bolts strong enough to secure the sub-holders to the tool holders.